Composite metal stock



Sept. 19, 1939. T. B. CHACE 2,E73,433

COM POS ITE METAL STOCK Original Filed May 13, 1937 57062220/ mamas ,5. 6/7006 WWW mzw Patented Sept. 19, 1939 UNITED STATES PATENT OFFICE Clad Metals Industries corporation of Illinoisv Original application May Inc., Chicago, 111., a

13, 1937, Serial No.

Divided and this application February 7, 1938, Serial No. 189,098

4 Claims.

My invention relates, generally, to mould constructions, and it has particular relation to the construction of moulds used in the production of composite slabs which may be rolled into various shapes and sizes. This application is a division of my copending application, Serial No. 142,387, filed May 13, 1937.

In the bonding and rolling of some high corrosion resistant alloys to steel, the design and type of mould are of importance in making the process commercial and the product usable. Some of the copper alloys, such as silicon copper, are particularly fluid in the molten state and are very difficult to hold in this state on the surface of a steel i backingslab. Some of the other non-corrosive alloys, such as the high nickel coppers of from 20% to 40% nickel content, having melting temperatures up to 2400 F., or Monel metal or stainless steel having melting temperatures similar to I the steel backing, are diflicult to hold in the molten state because of the extremely high casting tem peratures involved. The mould must be liquidtight after having been preheated to temperatures of around 2200 F.

Large slabs having a thickness of ten to twelve inches must be preheated for five or six hours at this temperature and the mould forming a part thereof must be such that it will not burn out and will remain liquid-tight as a container for the molten flux during the preheating, as well as a container for the non-corroding metal which is cast in the mould after preheating. This casting operation difiers from ordinary casting in that the mould, in some cases, is preheated to a temperature above the melting point of the casting alloy and, since the base of the mould or backing member is made up of a relatively thick steel slab, the heat is maintained for a considerable period and the cast metal remains molten much longer than ordinary cast metal remains molten in a cold mould, in which case the cast metal solidifies quickly. In fact, for the cladding of some combinations, such for example as my silicon-copper alloys, it is necessary to prolong the molten state of the casting alloy to perfect a bond between the two.

In view of the foregoing, an object of my invention is the provision of a mould which can be rolled as a part of a composite slab either directly from the bonding heat or as soon as the cast metal has solidified and cooled to the maximum hot rolling temperature.

Another object of my invention is to provide an open-faced mould on which the depth can be readily regulated as the measuring means for determining the required thickness of the cast alloy in proportion to the steel backing metal.

Another object of my invention is to provide an open-faced mould which may be elongated by working, such as rolling.

Still another object of my invention is to provide an open-faced mould which will prevent greater elongation of the cast metal than the steel backing metal when the former is softer than the la er.

Another object of my invention is to so construct an open-faced mould that spreading of the cast metal over'the sides of the base metal is prevented when the former is softer than the latter.

A still further object of my invention is to shape a base metal slab having integrally formed sides and up-turned ends so that it will form an openfaced mould into which a cladding metal can be cast.

Other objects of my invention will, in part, be obvious and in part appear hereinafter.

Accordingly, my invention is disclosed in the embodiment hereof shown in the accompanying drawing, and it comprises the features of coristruction and arrangement of parts which will be exemplified in the description hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description, taken in connection with the accompanying drawing, in which:

Figure 1 is a view, partly in side elevation and partly in section, showing a mould construction in which a base metal slab is provided with a channel-shaped top section having its ends upturned; and

Figure 2 is a sectional view taken along the line 2-2 of Figure 1.

The utility and construction of my type of mould for the purpose of cladding by casting one metal on the upper surface of another, are of great importance. For instance, any size of slab or backing member may be chosen with respect to starting and finish size which best fits the requirements of a particular order or specification with a minimum of scrap loss. This permits using regular bloom sections requiring a minimum of processing before cladding.

Referring now particularly to Figures 1 and 2 of the drawing, there is shown a mould construction which consists only of a base metal slab I5. As there illustrated, slab 15 is provided having its ends I6 turned upwardly to form, with side flanges I1 and the top surface II, a mould for receiving cladding metal. For instance, for a composite slab of about five inches in thickness with a 10% cladding of a non-corroding alloy, the web of the backing member 15 would be four and onehalf inches thick, with the side flanges 11' extending up from the surface "about one-half inch. The ends of the slab 15, which slab may be about six feet in length, are bent upwardly about onehalf inch, thereby closing the ends of the mould without requiring the welding of end members therein.

The usual cladding thickness is of the order of 10% to 20% of the composite stock and the height of the flanges l1 and the extent of the upward inclination of the ends is regulated accordingly:

On the first pass through a rolling mill, the ends are entered more readily between the rolls because they are tapered in thickness by the upward inclination of the backing member and the level surface of the cladding layer. Therefore these ends on the first pass are either not reduced or not as greatly reduced as the rolls compress to the thicker five inch section and, although the softer cladding metal elongates out over the thinner end sections to some extent, it does not project over the ends of the slab. This prevents the curling of the slab during rolling. These ends 16 may be turned up for a length of from three to four inches from each end while the slab is hot and, as the extent of bending is not important, as long as it is at least as much as the height of the side flanges 11, the operation can be performed on a rough forging press.

In practice, the ends 16 of slab 15 are upturned, either cold or after heating, the surface 18 is cleaned by acid or sandblasting and is lined with flux, slab 15 is heated, the mould space is filled with molten cladding metal and the cladding .metal solidifies and bonds to surface I8, the up turned ends of the flanges 11 may or may not be cut off, and the composite slab is rolled to the desired thickness.

It is apparent that there are several manners by which this mould construction can be made. The channel-shaped slab may be heated and its ends turned up to the desired height in a forge. The top surface can be cleaned before or after the ends are turned up and flux put in the mould space to prevent oxidation of the welding surface. If the slab is not hot enough after turning up its ends, it may be reheated and then the cladding metal may be poured into the mould space to float away the flux and bond to the welding surface.

There are several cladding metals which can be cast and bonded to the slab I5, such as stainless steel, copper, silicon copper, Monel metal, nickel alloys and others. The cladding metal to be cast will depend on the use to which the slab is to be put.

The fluxes used to cover the surface to be welded will depend on the cladding metal used. Borax is probably the most useful flux material, but any material which has a lower melting point than the cladding metal and which will prevent oxidation of the welding surface may be used. Fluxes especially suitable for cladding copper and silicon copper to a steel slab are mixtures of nickel powder, copper powder, powdered dehydrated borax, pitch and silicon powder.

Another method of preventing oxidation of the cleaned welding surface is to heat the slab in a reducing or non-oxidizing atmosphere. This might be done by heating in a furnace containing nitrogen, hydrogen, or carbon monoxide, or any mixture of these gases.

Since the ends of the flanges 11, after being turned up, project above the height of the mould wall and do not serve to retain the cladding metal, they can be cut off or hammered down level with the top of the web, before or after the mould is filled with cladding metal.

An alternative to upturning the ends is to close off the ends by upsetting the ends of the slab to produce a wall of the desired height between the side flanges H.

Since certain further changes may be made in the'foregoing mould construction, and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter shown in the accompanying drawing or described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. Composite metal stock adapted to be reduced in thickness and increased in area from a relatively thick slab to a relatively thin plate or sheet, comprising a thick slab of backing metal having a mould space for the reception of fluid cladding metal upon the upper face thereof, said mould space being defined by integral side flanges of a transverse thickness relatively small as compared to the vertical thickness of the slab itself, a layer of cladding metal cast into said mould space and integrally bonded to the face of the slab, the thickness of the backing metal being of the order of five to ten times as great as the thickness of the layer of cladding metal, the end of the slab being inclined upwardly to define the end of the mould space whereby the ratio of thickness of the backingm'etal to facing metal is increased at the end and the tendency of the facing metal to be displaced, by rolling, beyond the end of the backing metal is counteracted.

2. Composite metal stock adapted to be reduced in thickness and increased in area from a relatively thick slab to a relatively thin plate or sheet, comprising a thick slab of backing metal having a welding face defined by a mould consisting of flanges extending upward along the side edges of the slab, said flanges lying within the lateral confines of the slab, and the ends of the slab being inclined upwardly to close the ends of the mould space at substantially the same level as the tops of the flanges along the main part of the body of the slab, said inclined ends producing a tapering oil? of the mould space at the ends of the slab, a layer of facing metal cast into the mould space and firmly bonded to the backing slab, the tapering off of the ends of the mould space tapering the thickness of the cladding metal and tending thereby to keep the cladding metal from being rolled off the end, the upward inclination of the ends also reducing the thickness of the ends and facilitating initial entry of the end of the slab between the rolls.

3. Composite metal stock adapted to be reduced in thickness and increased in area from a relatively thick slab to a relatively thin plate or sheet, comprising a thick slab of backing material of a channel shaped cross section including side flanges of a height of the order of one-tenth to one-fifth of the thickness of the body of the slab, and having its ends inclined upwardly so that the bottom wall of the channel lies at a level substantially even with the tops of the flanges along the sides of the main part of the slab, said side flanges and upwardly inclined ends defining a mould space into which is cast a layer of cladding metal to form a composite slab, the ends of the composite slab being reduced in thickness by the being oi a height of the order of one-fifth to onetenth the thickness 0! the slab and the ends of the slab being. inclined upwardly to bring the bottom of the channel up to a level substantially even*with the tops of the flangesalong the central part of the slab, whereby a mould space tapering on in depth at the ends is provided.

THOMAS B. OHACE. 

